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Mesenchymal stem cells (MSCs) have been used for clinical application in tissue engineering and regenerative medicine (TERM). To date, the most common source of MSCs has been bone marrow. However, the bone marrow aspirate is an invasive and painful procedure for the donor. Thus, the identification and characterization of alternative sources of MSCs are of great importance. This study focused on the characterization of stem cells from human exfoliated deciduous teeth (SHED) compared with dental pulp stem cells (DPSCs) and bone marrow-derived mesenchymal stem cells (BMMSCs).We have compared "stemness" such as the proliferation rate and the expression of stem cell marker of DPSCs, SHED, and BMMSCs. In addition, gene expression profile of DPSCs and SHED were analyzed by using DNA microarray.All cells isolated from the three sources exhibited MSC characteristics including a fibroblastic morphology, and the expression of mesenchymal stem-cell markers. The proliferation rate of SHED was significantly higher than that of DPSCs and BMMSCs (P0.05). The comparison of the gene expression profiles indicated 4386 genes with a changed expression between DPSCs and SHED by 2.0-fold or more. Higher expression in SHED was observed for genes that participate in pathways related to cell proliferation and extracellular matrix, including several cytokines such as fibroblast growth factor and tumor growth factor beta.Because of its advantages of a higher proliferation capability, abundant cell supply, and painless stem cell collection with minimal invasion, SHED could be a desirable option as a cell source for potential therapeutic applications.

Purpose: The study aims to evaluate if human keratinocyte growth factor (hKGF), secreted after transduction of murine salivary glands with adenoviral vectors, can prevent oral mucositis resulting from radiation. Experimental Design: Two serotype 5 adenoviral vectors encoding hKGF were constructed: AdEF1α-hKGF and AdLTR2EF1α-hKGF. Female C3H mice, 8 weeks old, were irradiated by single (22.5 Gy) or fractionated (5 × 8 Gy for 5 days) doses to induce oral mucositis (ulcers on tongue). One day before irradiation, the above viral vectors or an empty vector, Adcontrol, was given (1010 particles per gland) to both submandibular glands by retrograde ductal instillation. Each experiment included five groups: no irradiation and irradiation (±Adcontrol, AdEF1α-hKGF, or AdLTR2EF1α-hKGF). Blood, saliva, submandibular glands, and tongue were collected on day 7 for single-dose studies or day 10 for fractionated dosing. hKGF levels were measured by ELISA. Results: In three separate single-dose irradiation experiments, lingual ulcers were dramatically reduced after either KGF-expressing vector. Similarly, in two separate fractionated irradiation experiments, the hKGF-expressing vectors completely prevented ulcer formation. QPCR data indicated that ∼107 to 108 particles of each vector remained in the targeted submandibular glands at the terminal time. Transgenic hKGF protein was found at high levels in saliva, serum, and submandibular gland extracts. Conclusions: hKGF gene transfer to salivary glands prevented radiation-induced oral mucositis in mice. This proof of concept study suggests that transgenic hKGF secreted from transduced salivary glands may be useful clinically to prevent oral mucositis caused by radiation.

Salivary glands have proven to be unusual but valuable target sites for multiple clinical gene transfer applications. Access to salivary glands for gene transfer is easy. Multiple studies in animal models have yielded proofs of concept for novel treatments for damaged salivary glands following therapeutic irraditation, in Sjogren's syndrome, and for gene therapeutics systemically by way of the blood-stream and locally in the oral cavity and upper gastrointestinal tract.

There is no satisfactory conventional treatment for patients who experience irreversible salivary gland damage after therapeutic radiation for head and neck cancer or because of Sjogren's syndrome. Additionally, if most parenchyma is lost, these patients also are not candidates for evolving gene transfer strategies. To help such patients, several years ago we began to develop an artificial salivary gland. In the present study, we used a non-human primate tissue source, parotid glands from rhesus monkeys, to obtain potential autologous graft cells for development of a prototype device for in situ testing. Herein, we present 3 major findings. First, we show that primary cultures of rhesus parotid gland (RPG) cells are capable of attaining a polarized orientation, with Na(+)/K(+)-adenosine triphosphatase, zonula occludens-1, and claudin-1 distributed in specific domains appropriate for epithelial cells. Second, we show that RPG cells exhibit 2 essential epithelial functions required for graft cells in an artificial salivary gland device (i.e., an effective barrier to paracellular water flow and the generation of a moderate transepithelial electrical resistance). Third, we show that RPG cells can express functional water channels, capable of mediating directional fluid movement, after transduction by adenoviral and adeno-associated virus type 2 vectors. Together these results demonstrate that it is feasible to individually prepare RPG cells for eventual use in a prototype artificial salivary gland.